Tap Rule

[eolson]

I have a lab with multiple panels. 1 - 3 pole 70 amp breaker feeds 2 panels about 30' apart. We are installing new distribution panels and re-feeding all existing panels. My question is , We have a new 3 pole 70 amp breaker with new feeders going into 1 of the panels, Existing condition is that the 2 panels do not have mains and wire come into 1st panel and there is a double lugs with wires going to 2nd panel. Being a full size tap am I required to install a breaker in the 1st panel to feed the 2nd panel or is the existing condition correct .

 

[kingpb]

When you say full size tap, are you saying that the cable to the second panel is sized for the full 70A of the breaker feeding the first panel, and the second panel is rated for at least 70A?

 

[eolson]

Yes the cable feeding the 2nd panel is the same size.

 

[infinity]

You have a "splice" not a tap so tap rules do not apply.

 

[eolson]

So no need for any breakers in the 2 panels? Just the breaker in DP panel that feeds the 2 panels ? Didn't seem right to me . But thanks for the help.

 

[petersonra]

I have a lab with multiple panels. 1 - 3 pole 70 amp breaker feeds 2 panels about 30' apart. We are installing new distribution panels and re-feeding all existing panels. My question is , We have a new 3 pole 70 amp breaker with new feeders going into 1 of the panels, Existing condition is that the 2 panels do not have mains and wire come into 1st panel and there is a double lugs with wires going to 2nd panel. Being a full size tap am I required to install a breaker in the 1st panel to feed the 2nd panel or is the existing condition correct .

as long as the bus on the panels you are feeding exceeds 70A rating you don't need to do anything.

the other posters are right hat this is not a tap.

 

[jap]

So no need for any breakers in the 2 panels? Just the breaker in DP panel that feeds the 2 panels ? Didn't seem right to me . But thanks for the help.

It's the word "Tap" that throws most people off.

It's very common to hear, "We're gonna tap off of that and go to there" or " Then we're gonna go tap a keg when we get done".

The word "Tap" itself only means that your going to connect something to something.

In electrical, you have to look at it as a 2 step process.

Yes, they did "Tap" off of the 1st panel to feed the 2nd one by connecting the wires going to the 2nd panel to the wires feeding the 1st panel, but, they did not decrease the size of the conductor to the 2nd panel.

In that case, the Overcurrent protection device feeding the 1st panel will protect the wiring to the 2nd panel because they are both the same size conductors.

Now.

If they had of reduced the size of the wire from where they made the tap to the 1st panel to the 2nd, then, that would have actually been a tap because the overcurrent device protecting the wire to the 1st panel would have been larger than what the smaller wire to the 2nd panel was designed to carry

That's when the actual "Tap Rules" come into play, and, there are different rules depending on the type of tap, and, how far those smaller conductors travel
before landing on some type of protection themselves.

JAP>

 

[don_resqcapt19]

It's the word "Tap" that throws most people off.

It's very common to hear, "We're gonna tap off of that and go to there" or " Then we're gonna go tap a keg when we get done".

The word "Tap" itself only means that your going to connect something to something.

In electrical, you have to look at it as a 2 step process.

Yes, they did "Tap" off of the 1st panel to feed the 2nd one by connecting the wires going to the 2nd panel to the wires feeding the 1st panel, but, they did not decrease the size of the conductor to the 2nd panel.

In that case, the Overcurrent protection device feeding the 1st panel will protect the wiring to the 2nd panel because they are both the same size conductors.

Now.

If they had of reduced the size of the wire from where they made the tap to the 1st panel to the 2nd, then, that would have actually been a tap because the overcurrent device protecting the wire to the 1st panel would have been larger than what the smaller wire to the 2nd panel was designed to carry

That's when the actual "Tap Rules" come into play, and, there are different rules depending on the type of tap, and, how far those smaller conductors travel
before landing on some type of protection themselves.

JAP>

That is a very good example of "field language" vs "code language". That is the way terms are used in the field is often very different than the way the code used that same term. We have to be very careful that when we are dealing with a code question, that we only use the term as it is defined in the code.

Tap Conductor. A conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4.

 

[kwired]

Well if using proper NEC terminology anything covered by 240.21(B) is a "feeder tap"

 

[petersonra]

Well if using proper NEC terminology anything covered by 240.21(B) is a "feeder tap"

I suppose you could have a service tap as well.

 

[kwired]

I suppose you could have a service tap as well.

Though NEC won't really call them taps, they are just service conductors that are spliced together. There also is branch circuit tap conductors sometimes -240.21(A).